"I'm going to ask Fred Smith, the founder of Federal Express, to come work for the government for three months at Immigration and Custom Enforcement and show these people. We need to have a system that tracks you from the moment you come in, and then when your time is up ... however long your visa is, then we go get you. We tap you on the shoulder and say, 'Thanks for coming. Time to go.'"

Giuliani last week predicted that Trump would be making additional changes to his immigration plan culled from Christie's presidential bid, including the "Fedex" plan and a call to make the Department of Homeland Security's E-Verify employment eligibility verification program compulsory.

It was only one of several Christie positions that Trump embraced this weekend.

While speaking at U.S. Sen. Joni Ernst's "Roast and Ride" fundraiser in Iowa on Saturday, Trump also appeared to have borrowed Christie's approach to reforming veterans health care.

"For our veterans, it means a guarantee that they can seek medical care at either a VA facility, or a private medical doctor, with us paying the cost," said Trump.

In an October 2015 interview with CNN, Christie promised that "any veteran, while they're waiting for us to fix the mess at the VA, you present your veterans card to any doctor, healthcare provider or hospital in America, you will get your health care and get it paid for by the government."

Trump also seemed to borrow lines from Christie when he said he would oppose the Environmental Protection Agency's "Waters of the US" rule-making proposal and support the Renewable Fuel Standard.

In 2014, the EPA proposed expanding its regulatory authority under the Clean Water Act to cover ponds and other isolated wetlands interspersed in nation's farmlands, something detested by Iowa's farmers.

"We are going to end the EPA intrusion into your family homes and family farms for no reason," Trump said Saturday, calling the Waters of the U.S. rule "a disaster."

In March 2015, Christie laid the groundwork for his presidential run at the Iowa State Fairgrounds, Christie derided the Waters of the U.S. rule "nothing more than a power grab from Washington D.C."